Pluripotent stem cells can be derived from embryos or induced from adult cells by reprogramming. They are unique among stem cells in that they can give rise to all cell types of the body. Recent findings indicate that a particularly 'open' chromatin state contributes to maintenance of pluripotency. Two principles are emerging: specific factors maintain a globally open chromatin state that is accessible for transcriptional activation; and other chromatin regulators contribute locally to the silencing of lineage-specific genes until differentiation is triggered. These same principles may apply during reacquisition of an open chromatin state upon reprogramming to pluripotency, and during de-differentiation in cancer.
Bibliographical noteFunding Information:
We thank E. Bernstein, F. M. Koh, M. Sachs and three anonymous reviewers for constructive comments. E.M. is a Joseph H. and Belle R. Braun senior lecturer in life sciences and is supported by the Israel Science Foundation (ISF 215/07 and 943/09), the Israel Cancer Research Foundation, the Israel Ministry of Health (6007), the European Union (IRG-206872 and 238176) and an Alon Fellowship. A.A. is a Safra fellow. Work in the M.R.-S. laboratory is supported by a US National Institutes of Health Director’s New Innovator Award, the California Institute for Regenerative Medicine and the Helmsley Trust.